Encapsulation of Essential Oil-Cyclodextrin Inclusion Complexes in Electrospun Pullulan Nanofibers: Enhanced Storage Stability and Antibacterial Property for Geraniol and Linalool

Abstract

In this study, the gamma-cyclodextrin (γCD) inclusion complexes with essential oil (EO) compounds linalool and geraniol were encapsulated in pullulan nanofibers using an electrospinning technique. The nanofibers were produced with the initial EO content of ~ 11% (w/w) and ~ 74 to 77% of these volatile compounds could be preserved in pullulan/EO-γCD nanofibers due to inclusion complexation. On the other hand, only ~ 15 to 23% of EO could be kept in the case of pullulan/EO nanofibers in the absence of γCD. The EO-γCD inclusion complexation also ensured improved thermal stability for EO compounds, and their volatilization shifted from ~ 119–139 to ~ 239–292 °C ranges for pullulan/EO-γCD nanofibers. Moreover, pullulan/EO-γCD nanofibers displayed substantial long-term storage stability and, ~ 48 to 64% of EO content was still preserved even after 4 weeks, while this ratio was in the range of ~ 0.3 to 4.5% in the case of pullulan/EO nanofibers. The pullulan/geraniol-γCD nanofibers displayed an effective antibacterial activity against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, and overwhelmingly better performance compared to pullulan/geraniol nanofibers due to the inclusion complexation. Briefly, EO-incorporated nanofibers were generated using GRAS γCD molecules and an edible pullulan polymer, and this approach can be a promising alternative to be effectively used in the food industry for the encapsulation and delivery of volatile EO compounds.